Most people recommend replacing the trigger pin (with CGW floating trigger pin), the trigger return spring (with CGW reduced power trigger return spring), firing pin retaining pin (with CGW firing pin retaining pin) and the firing pin block spring (with the reduced power spring also from CGW).
I've heard some people have a slide release shaft break around 10,000 rounds and others have gone 3 or 4 times that many rounds without it breaking.
I've bought mostly pins and springs as spares. Due to some other parts replacements (replaced factory triggers/hammers/sears with CGW and CZ USA parts) I have spares of new parts (some never shot before they were replaced).
One tip - when you order parts, order enough to make the shipping worth it. I wasn't ordering parts to replace broken parts, but for upgrades. So when I ordered a hammer/sear I'd go ahead and order small parts - combination of those that might break and those that might get lost when working on a pistol). Up to a point, the shipping can be the same, whether you are ordering 2 parts or 30.