Originally Posted by asturiano
So a pump stitch in essence is a tunnel stitch? If that is the case the strength of the shoe will be determined by how we maintain the sole/insole?
Also I guess there is not possibility to resole in a such a shoe
Well, a pump stitch is used for light duty shoes that are to be worn around the house and, perhaps, to the occasional formal occasion (depending on the style). They are not designed for heavy use in walking outdoors, etc., so wear should be minimal. Perhaps the heaviest wear would come from dancing! If the shoe is properly made, then the stitches are protected by the outsole and insole (it is at the interface where the two meet), so absent heavy wear or abuse there should be no need for special treatment of the insole and outsole. Note that there are two ends to the thread, so that the two ends are alternatingly weaving in/out of the insole and outsole.
The shoe should be able to be resoled -- a new outsole would be put on in the exact same manner as the original. I should think you would need the original last to do this in a quality way. Also, someone who knows how to do it, which is becoming rarer by the year.