I believe WWE did own the rights to that phrase and many others Rock came up with. When he joined the board at TKO, he was given the rights as part of their agreement.
This is actually the WCW world heavyweight championship. WWE kept the design but remade the belt with the WWE logo when they reintroduced it late 2002. This belts main plate is flat, the redesigned one is somewhat curved to wrap around the wrestlers waist.