In order of worst to best case scenario the human body will reject, wear down, or scar around any and all implanted foreign materials or objects. Implants of every type have a shelf life, some long enough to never worry about removal. The best method to secure implants are to bones, but the only nearby bones for the stomach are the hips and spine, with organ cavity linings being problematically in the way for most attachments. For the digestive system it would need to be extremely resistant to corrosion and it would also need to be nontoxic as it would inevitably enter the bloodstream. Even teeth fillings are only rated for about a decade at most.

So, to be blunt, no such technology exists on this earth nor any speculation on how it ever might.