WordPress insert_user

$user = wp_insert_user( array ( 'ID' => $user_id,
                'user_login' => $email,
                'user_email' => $email,
                'first_name' => $first_name,
                'last_name' => $last_name,
                'display_name' => $display_name,
                'user_pass' => $password) ) ;

if ( is_wp_error($user) )
{
    debugPrint(" ".$user->get_error_message());
    return false;
}