$modx->setOption(xPDO::OPT_SETUP);
$user = $modx->newObject('modUser', array(
    'username' => $username,
    'password' => $password,
    'sudo'    => 1,
));
$profile = $modx->newObject('modUserProfile', array(
    'email' => $email,
));
$user->addOne($profile);
$user->save();