$new_user_id = wp_insert_user(array(
'user_login' => $user_email,
'user_pass' => $user_pass,
'user_email' => $user_email,
'first_name' => $user_first,
'last_name' => $user_last,
'user_registered' => date('Y-m-d H:i:s'),
'role' => 'subscriber'
)
);