If you're using WHM and cPanel, load up CSF rather than APF and BFD - it's a MUCH better program!

As for the logs, it looks like someone is trying to hit your site hard, however the bigger concern is the usernames in that list, are they the usernames from your server? If so, how did they get a complete list of your users on the server? Would seem like your passwd file or group file has been exposed somewhere.