1_working.jsx

import PropTypes from 'prop-types';
import React from 'react';
import CustomerMatch from '../containers/CustomerMatchContainer';
import {BrowserRouter as Router, Link, Route} from 'react-router-dom'

export default class ServiceParentComponent extends React.Component {
  render() {
    return (
      <Router>
        <div>
          <Route path="/" exact={true} render={() => (
            <div>
              <h3>Services App</h3>
              <Link to={`/customers/match`}>Customer Match</Link>
            </div>
          )} />
          <Route path="/customers/match" component={CustomerMatch} />
        </div>
      </Router>
    );
  }
}

2_not_working.jsx

import PropTypes from 'prop-types';
import React from 'react';
import CustomerMatch from '../containers/CustomerMatchContainer';
import {BrowserRouter as Router, Link, Route} from 'react-router-dom'

export default class ServiceParentComponent extends React.Component {
  render() {
    return (
      <Router>
        <div>
          <Route path="/" exact={true} component={WelcomeScreen} />
          <Route path="/customers/match" component={CustomerMatch} />
        </div>
      </Router>
    );
  }
}

const WelcomeScreen = (props) => {
  <div>
    <h3>Services App</h3>
    <Link to={`/customers/match`}>Customer Match</Link>
  </div>
}