foot pain during long rides....

Could me multiple things, but these are the ones I would suspect from your description.

First, cycling shoes should be tight, so if they are loose, which allows your foot too much movement, then you could easily get sore feet like you are describing. In cycling shoes, too large is worse than too small.

SPD's are made for mountain biking and although you can use them on the road, they do present a small platform, which can cause hot spots (i.e. concentrated pressure in a small area causing the pain). I would honestly recommend a pedal with a larger platform... something like Shimano SPD-SL (if you want Shimano), or my favorite would be Speedplay (don't get fooled by the small pedal, the cleat is the shoe interface and represents a sizable platform).

Gel inserts would more than likely make it worse since they offer no support at all. I've had great success with Specialized BodyGeometry insoles (my wife has them in all her shoes).

Finally, bike fit... could be your entire fit being off causing this issue, or something small like the cleat position being off causing it. Make sure the center of the cleat is inline with the center of the ball of your foot.

Thanks for the response as I have a 65 mile group ride tomorrow and wondering do I wear thick or thin socks. I think the shoes are a lil big as I can wiggle toes very easily. I did have a prof bike fit from awesome LBS and got larger shoe as one foot is bigger than the other (no ones perfect!)
My budget restricts me from making any big purchased changes although the wider pedal base makes sense. Think I will play with some changes with insoles/socks and see how it goes. I will also go back to shop and see what they advise.
Joy

Thick socks is the fix! So obviously shoes are a lil too big. I wore my fav running socks "feetures" which are thicker and after 75 mile ride NO foot pain!!!