Thicker tomato sauce on the pizza makes the cheese more slippery After reading the advice about tomato sauce in this answer, I decided to try straining the sauce to remove water and see what it did to the crust. 

I let the water drain out of a jar of tomato sauce by leaving it in a cheesecloth-lined colander. The sauce went down to almost half its volume, and I had to trowel it on the crust almost like spackle. 

As usual, I used a pizza stone, and an oven that at about 500&#176;F. The pizza takes about 7 or 8 minutes to cook, like this, rotating it twice in that time. I don't pre-heat the crust. 

For this pizza, I used supermarket whole-wheat pizza dough (Stop and Shop makes a wonderful dough, incidentally), half-skim mozzarella, Barilla marinara sauce, fresh basil, and sauteed mushrooms and garlic. The pizza was delicious! The crust was thicker than usual, and lighter. 

It seemed to me that the cheese was, for want of a better description, a bit looser than it usually was, and had a tendency to slide off the rest of the slice when you took a bite. 

If I repeat this (and I will), I'll likely use even more of the same, strained sauce, since I got some requests for "more sauce, please, I could barely taste it." How can I "anchor" the cheese a bit? Mix a little cheese in with the sauce so it'll grab ahold of the cheese? Pre-bake the crust with sauce on it for a minute or two? (I'm not sure what that would do.) A staple gun, perhaps?
If you have to trowel the sauce on the crust it is too thick.  There is a "right" consistency that will prevent the pizza from being too watery but will still have enough moisture to allow the cheese and sauce to fuse somewhat.

On the other hand, you could just ignore that the cheese isn't fusing.  I've eaten thousands of pizzas in Italy and most of them are more watery that what you'd get in the US and the cheese usually does not fuse with the sauce.  Probably because it's only in the 800°F brick oven for about 3 minutes!  Enough time to cook the thin crust, barely melt the cheese, and that's it.

If you really want that cheese to fuse, I would suggest a slightly more watery sauce, and more heat from the top.  Turn on the broiler for the last minute or so until the cheese starts to bubble.  This will also help evaporate some of the extra water in the sauce.