I'm going to start a friendship with someone my fwb is insecure about
Why do you think you want to start that friendship?
He thinks he's so hot shit around me so I'm going to bring in another guy who's smarter than him
You can become friends with whoever you want. However, if you're doing this just out of spite it's the wrong reason.
My friends with benefits said I was weak and that he picked on me because I was scared of him and he liked that.
It sounds like your FWB may not be worth keeping around. Are you sure you don't want to start a friendship up with the other person because you are in need of a real friend? Think things through and do what's best for you.