That is called an impeller. You can probably just pull it out and clean it. I have found mine tend to get funk built up and pull it out and clean the best I can. It is magnetic, so might be a little hard to pull out, or, you might be afraid that it will break (I was concerned myself, at first). Once you clean it, try it again and see if, both the noise and it works again. If not, check with the maunfacturer and see if they have replacements....
How long will the fish live without moving water?
I'm not sure, in a nano, (I do know, nanos are smaller and bad things can happen very fast) but you could use a ph for water movment.
Any chance you can update "my info" with your tank/ewuip/critters?