Fail2ban is a popular intrusion prevention software written in python that is intended to protect your server from single-source brute force attacks. By default it will watch your SSH service on port 22 but it also does much more.
You can find many filters on the web, or write your own, that match a specific set of rules based on some log. Fail2ban can also be set to block the IP address of people trying to log into your WordPress website.
First, add the following code to functions.php in your WordPress theme. This will return a 403 status for incorrect login attempts.