What kind of gasket is provided with the pump ?

If it is some fancy dancy gasket with some kind of peel off protective film.... then maybe that is fine...

But if it is a normal gasket which you can touch with your fingers and is not sticky... there is no way I would install it on my car without sealer. I use Aviation Gasket cement on my water pump gaskets...and I let them tack up before installing... messy and sticky... just what a sealer is supposed to be....LOL.. be sure to have alcohol on hand for cleaning it off you or clothes... no...just be sure it does not get on clothes...

I put a thin layer of sealer on all four surfaces...

Just be sure on any gasket install that all surfaces are clean enough to eat off of...