Add a column before username in the users profile table

Ok, I solved it by unsetting $defaults and reconstructing it after adding the company

function add_company_column($defaults) {
    unset($defaults);
    $defaults['company'] = __('Company');
    $defaults['username'] = __('username');
    $defaults['name'] = __('Name');
    $defaults['email'] = __('Email');
    return $defaults;
}