wp_insert_user on custom field code example
Example: wp_insert_user
$website = "http://example.com";
$userdata = array(
'user_login' => 'login_name',
'user_url' => $website,
'user_pass' => 'plain_password' // When creating an user, `user_pass` is expected.
);
$user_id = wp_insert_user( $userdata ) ;
// On success.
if ( ! is_wp_error( $user_id ) ) {
echo "User created : ". $user_id;
}