/**
 * Register new rest route
 */
	add_action( 'rest_api_init', function () {
		register_rest_route( 'wp/v2/', 'users/register', array(
			'methods' => 'POST',
			'callback' => 'my_awesome_func',
		) );
	} );

 function my_awesome_func ( WP_REST_Request $request ) {
	$parameters = $request->get_params();
	$username = sanitize_text_field($request->get_param( 'username' ));
	$email = sanitize_text_field($request->get_param( 'email' ));
	$password = sanitize_text_field($request->get_param( 'password' ));

	if(empty( $username )) {
		return new WP_Error(400, "Username field 'username' is required.", 'wp-rest-user');
	}

	if(empty( $email )) {
		return new WP_Error(400, "Email field 'email' is required.", 'wp-rest-user');
	}

	if(empty( $password )) {
		return new WP_Error(400, "Password field 'password' is required.", 'wp-rest-user');
	}

	if(!username_exists( $username ) && !email_exists( $email )) {
		$user_id = wp_create_user( $username, $password, $email );
		if(!is_wp_error( $user_id )) {
			wp_send_new_user_notifications($user_id, $notify = 'both');
			return new WP_REST_Response( 'User ' . $username . 'has been successfully created.' );
		} else {
			return new WP_Error(409, 'Could not create new user.');
		}
	} else {
		return new WP_Error(406, "Email already exists, try resetting your password.", 'wp-rest-user');
	}

	return username_exists($username);
 }