Login to your server as root.
Install wp-cli as stated here:
http://wp-cli.org/#installing
After installing WP-CLI
Open file: /etc/cagefs/conf.d/wp.cfg
using:
$ nano /etc/cagefs/conf.d/wp.cfg
Add the following content to that file and save.
[wp]
comment=wp
paths=/usr/local/bin/wp
And then run:
$ cagefsctl --force-update
Now all users who have SSH access can use wp command.