It seems there is no way to manually order users in a WordPress site. You can choose between some available options when using get_users or WP_User_Query and that’s it. There is even no filter to allow manipulation of ordering.
And I needed this for a site I was working on: coregroup.no
Enter Simple User Ordering – a plugin that I wrote which allows admins to manually ordered WordPress Users with a simple drag’n'drop.
Check it on Github: https://github.com/cek125i/simple-user-ordering
Interface is heavily influenced by Simple Page Ordering and the name honors it