Pumps went through a properly scruffy patch for a while there, all synthetic uppers and glued soles that gave up after a few outings, and they've come back better for it. The good ones now actually hold their shape instead of going flat and sad by lunchtime, which is a low bar but one the high street used to fail constantly.
The difference between a pair that lasts and a pair that lets you down is mostly in things you can check with your hands before you've even paid. Pick one up and flex the sole, a decent pump bends at the ball of the foot and springs back, not a dead crease across the middle. Press a thumbnail into the upper, leather or a good leather look gives slightly and recovers, cheap PU stays dented or feels like it's wearing a plastic raincoat. Look inside at the lining, a proper one is stitched down neatly with no glue showing at the edges, and any trim or bow should be sewn on rather than stuck, because stuck always lifts, usually at the worst possible moment on a wet pavement. Hardware, if there is any, should feel solid rather than light and tinny, a cheap buckle looks fine on the shelf and then goes dull and slightly green within a month.
Where pumps genuinely come up short is distance and support. They're flat but they're not trainers, there's often very little arch structure and not much underfoot padding, so a long walk across a city or a full day on your feet will tell on you by mid afternoon whether you want it to or not. If you've got a higher arch or you're on hard floors all day, this is the wrong shoe, however pretty the point looks in the box. For that you want something with more built in support, and no amount of gel insoles entirely fixes a flat that was never designed to hold you up.
On colour, the ones that get worn into the ground rather than just admired are a mid camel or tan, navy, and a proper black with a matte rather than shiny finish, because patent shows every scuff and scratch within a week. Fit wise, go half a size down from your trainer size as a starting point and try both feet, pumps are notorious for coming up slightly long at the toe and slightly loose at the heel at the same time, which is an uncomfortable combination to live with. Walk a few steps in the shop, not just to the mirror, and check your heel doesn't lift with each step, a slipping heel only gets worse once the lining beds in.
Reach for pumps on the days you need to look pulled together without thinking about your feet for more than ten minutes at a time.