This Gates water pump uses a 3D cast impeller - not the cheap stamped and spot-welded metal of cheaper manufacturers. Gates pumps are a guaranteed good fit and seal, and will outperform and outlast the competition.
Water pump replacement is recommended every 50,000-60,000 miles for peace of mind. Unlike the timing belt, when your water pump decides to go meet its maker, you could be replacing many components including your engine if you aren't lucky. It's best to just replace it preventatively, along with a timing belt, to avoid any unpleasant surprises.
This kit comes with gaskets.