There's no need to try and make a ResultSet from an insert, it's not going to give you back any resultset data.
public function insertme()
{
$sel = new Sql($this->adapter);
$s = $sel->insert('users');
$data = array(
'fname'=>'fisdsds',
'lname'=>'sdsdsdme',
'email'=>'sdsdsds',
'pword'=>'dsdsds'
);
$s->values($data);
$statement = $sel->prepareStatementForSqlObject($s);
$result= $statement->execute();
//print_R($result);
return $result;
}