I have a pair of shoes that still look great outside but are worn out inside such that they cause a bit of discomfort. They are men shoes that one usually wears in the office. They have about 1cm thick sole made of some sort of solid rubber thing (not sure of what it is sorry) which got thin and worn out at the front mostly and at the heel a bit. They were also worn out at the bottom outside so I have got them repaired (they glued a new sole at the bottom and reconstructed the heel). At that time I could not do that myself. After that the surface inside became even more uneven. Complained to the guys and they tried to fix it by applying a thin piece of leathet on top of the uneven surface which did not really fix it Tried some soft insoles but did not work well. Anything I can do myself at home to make the surface inside even and nice and natural? Is it the same technique one would apply to make better arch support for a high arch foot?
I had the same problem and bought hard insoles. They do not look very comfortable, but they actually are! Because they are harder than the soft leather insoles you might not notice the unevenness. If they are still uneven, you might be able to put a piece of leather between the hard insole and the shoe, but I doubt that will be necessary.
This is happening to me almost every time. Almost every shoe I bought in last decade had sole (to be more precise - heel) made with hollow compartments. Not only does this kind of sole deform and break up from inside, but it also wears unevenly and quickly on the bottom side and will open up holes after some time. The best solution I found so far is to fill those hollow compartments with silicone. This isn't ideal, because silicone is softer than the material soles are made of, so a good insole is needed, with some rigidity in the heel area (again, I resort to some DIY here). The main advantages of silicone is that it creates water-tight seal, it's not as toxic as some glues and it's cheap.
Some tips: wear gloves, silicone is not easy to wash off and work in well ventilated area. Acid based silicone, which is the most common, releases acetic acid which is somewhat irritating. Silicone will probably need 24-48 to cure. I'm using regular "sanitary" silicone.