How can I get 3d model soldiers to move within Ursina?

Question

The following code creates a 3d world that allows the user to navigate with two weapons. Ten soldiers spawn within the world and everytime the user kills one, they respawn in a random position. My goal is to get the soldiers to be constantly moving within the four walls, but keep getting errors in my attempt to do so. I am using pycharm and the 3d engine, Ursina in order to do this.plz help.

    import timeit
from ursina import *
from random import uniform
from ursina.prefabs.first_person_controller import FirstPersonController


class Player(Entity):
    def __init__(self, **kwargs):
        self.controller = FirstPersonController(**kwargs)
        super().__init__(parent=self.controller)

        self.gun = Entity(parent=self.controller.camera_pivot,
                          scale=.012,
                          model="finalassets/shotgun/source/C96.FBX",
                          texture="finalassets/shotgun/textures/C96_Albedo.png",
                          position=Vec3(0.1, -.5, 0.98),
                          rotation=Vec3(1, -10, 3),
                          visible=True)

        self.ar = Entity(parent=self.controller.camera_pivot,
                         scale=.05,
                         position=Vec3(0, -.6, 1),
                         rotation=Vec3(15, 85, 5),
                         model="finalassets/ace/Source/ace.FBX",
                         texture="finalassets/ace/Source/textures/ACE_gloss.png",
                         visible=False)

        self.weapons = [self.gun, self.ar]
        self.current_weapon = 0
        self.switch_weapon()

    def switch_weapon(self):
        for i, v in enumerate(self.weapons):
            if i == self.current_weapon:
                v.visible = True
            else:
                v.visible = False

    def input(self, key):
        try:
            self.current_weapon = int(key) - 1
            self.switch_weapon()
        except ValueError:
            pass

        if key == "scroll up":
            self.current_weapon = (self.current_weapon + 1) % len(self.weapons)
            self.switch_weapon()

        if key == "scroll down":
            self.current_weapon = (self.current_weapon - 1) % len(self.weapons)
            self.switch_weapon()

        if key == "left mouse down":
            if self.current_weapon == 0:
                Bullet(model='sphere', color=color.white, scale=0.05,
                       position=self.controller.camera_pivot.world_position,
                       rotation=self.controller.camera_pivot.world_rotation)
            elif self.current_weapon == 1:
                Bullet(model='sphere', color=color.red, scale=0.1,
                       position=self.controller.camera_pivot.world_position,
                       rotation=self.controller.camera_pivot.world_rotation)

    def update(self):
        self.controller.camera_pivot.y = 2 - held_keys['left control']


class Bullet(Entity):
    def __init__(self, speed=50, lifetime=10, **kwargs):
        super().__init__(**kwargs)
        self.speed = speed
        self.lifetime = lifetime
        self.start = time.time()

    def update(self):
        ray = raycast(self.world_position, self.forward, distance=self.speed * time.dt)
        if not ray.hit and time.time() - self.start < self.lifetime:
            self.world_position += self.forward * self.speed * time.dt
        else:
            destroy(self)
            if ray.hit and isinstance(ray.entity, EntityWithHealth):
                entity = ray.entity
                entity.take_damage(1)
                if entity.health <= 0:
                    destroy(entity)
                    spawn_entities()

    def handle_collision(self, hit):
        pass


class EntityWithHealth(Entity):
    def __init__(self, **kwargs):
        super().__init__(**kwargs)
        self.health = 2

    def take_damage(self, damage):
        self.health -= damage

    def kill(self):
        destroy(self)
    def spawn(self):
        self.position = Vec3(
            uniform(-25, 25),
            0,
            uniform(-25, 25)
        )
        self.health = 2

app = Ursina()

Sky()

ground = Entity(
    model='plane',
    scale=(100, 1, 100),
    color=color.lime,
    texture='grass',
    texture_scale=(150, 150),
    collider='box'
)

wall = Entity(model="cube", collider="box", position=(0, 0, 50), scale=(100, 10, 50), rotation=(0, 0, 0),
              texture="finalassets/wall/textures/brick7.jpg", texture_scale=(35, 35), color=color.black)
wall2 = duplicate(wall, z=-50)
wall3 = duplicate(wall, rotation_y=90, x=-50, z=0)
wall4 = duplicate(wall3, x=50)

player = Player(position=(0, 1, 0))

entities = []

for _ in range(10):
    entity = EntityWithHealth(
        model="finalassets/soldier/soldier_airborne.fbx.glb",
        color=color.orange,
        position=Vec3(uniform(-25, 25), 0, uniform(-25, 25)),
        scale=0.0015,
        collider='box'
    )
    entities.append(entity)

def spawn_entities():
    for entity in entities:
        destroy(entity)

    for _ in range(10):
        entity = EntityWithHealth(
            model='finalassets/soldier/soldier_airborne.fbx.glb',
            color=color.green,
            position=Vec3(
                uniform(-25, 25),
                0,
                uniform(-25, 25)
            ),
            scale=0.0015,
            collider='box'
        )
        entities.append(entity)

spawn_entities()

def input(key):
    if key == 'space':
        spawn_entities()

def update():
    for entity in entities:
        direction = Vec3(uniform(-1, 1), 0, uniform(-1, 1)).normalized()
        speed = 3
        entity.position += direction * speed * time.dt

app.run()