How to make BottonNavigationBar route to different body Containers in Flutter

Question

I'm creating a simple app consisting of three pages, the only thing to be changed when using the navigation bar is the body. I need every body to be in it's own dart file. whenever I try achieving this and replace the text with another widget, I break the app.

Here's my code so far:

import 'package:flutter/material.dart';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Sample App';

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: _title,
      home: MyStatefulWidget(),
    );
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  int _selectedIndex = 0;
  static const TextStyle optionStyle =
      TextStyle(fontSize: 30, fontWeight: FontWeight.bold);
  static const List<Widget> _widgetOptions = <Widget>[
    Text(
      'Index 2: Account',
      style: optionStyle,
    ),
    Text(
      'Index 1: Locate a Store',
      style: optionStyle,
    ),
    Text(
      'Index 0: Home',
      style: optionStyle,
    ),
  ];

  void _onItemTapped(int index) {
    setState(() {
      _selectedIndex = index;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: _widgetOptions.elementAt(_selectedIndex),
      ),
      backgroundColor: Colors.amber[400],
      bottomNavigationBar: BottomNavigationBar(
        showSelectedLabels: false, // <-- HERE
        showUnselectedLabels: false, // <-- AND HERE
        items: const <BottomNavigationBarItem>[
          BottomNavigationBarItem(
            icon: Icon(Icons.manage_accounts),
            label: 'Account',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.search),
            label: 'Store Locator',
          ),
          BottomNavigationBarItem(
            icon: Icon(Icons.home),
            label: 'Home Page',
          ),
        ],
        currentIndex: _selectedIndex,
        selectedItemColor: Colors.amberAccent[400],
        onTap: _onItemTapped,
        iconSize: 35,
      ),
    );
  }
}

To sum it up, The Text widget need to be replaced with new body/container that's saved in its own dart file, and work with the navigation bar.