Water Pump Fittings

You're using what appears to be Chinese Garbage, That's likely why nothing's fitting. If your new pump came with that brass "thing", toss all of it and start over. No respectable manufacturer would supply **** like that.

It looks to me like that new brass fitting is too small anyway. If you got it from NAPA, try Autozone, Advance, Rock Auto, hell, even try the dealer.