It should definitely run the pump as pump motors are capacitor start usually. You may or may not be able to run everything else at the same time, but like I said, you're freezer/fridge isn't going to spoil food in the amt of time you'll be doing this.
Basically what I would do is run some Type UF 10/2 from your generator location to the pressure switch. REMEMBER TO TURN OFF YOUR BREAKER TO THE PUMP AT THE PANEL
I say that because if the power comes back on, and you are energizing the pump from BOTH the panel and the genny you'll have ummm, well, problems.
You should see two lines running away from the pressure switch. One is going to your well (load) the other is the power in (line).
The quick and dirty way would be to disconnect your LINE coming from the panel (AFTER turning the breaker off and testing it LOL! Live cats work well for this purpose...) Then cap it with wire nuts. Run the new temporary line to the same terminals and make sure they are tight. Don't worry about a strain relief or anything-this is an EMERGENCY measure. The other end gets a 240v plug that matches your generator. There is a Nema # such as L6-30R on the receptacle if you look closely. R stands for receptacle. What you need is an L6-30P (for Plug) to fit it.
Once you've double checked everything, plug it in and flip on the little circuit breaker (if it has one.)
There are other, more permanent ways to do this that would be better, but I'd really have to draw you a picture. The best thing to do is put a 50amp panel right next to your other panel and run a line from that to your generator. Then when the power goes out, you flip a 50A two pole breaker with a safety kit on it in your MAIN panel, which disconnects the subpanel from the service while you are using your generator. Basic lights and fridge, well and freezer get jumpers from the main panel to the sub so that they can be run either way. This is really a job for an electrician, but is well worth it in the long run. This way you simply plug in a heavy extension cord to your generator (in a shed outside?) and plug it into a weatherproof twistlock receptacle on the outside of your house to backfeed the subpanel when the power is off.
The reason for the 'safety kit' is basically it's two 50 amp breakers, one above the other, and with this simple switch, flipping one flips the other off. I did a lot of these conversions around Y2K.