You are experiencing normal seal wear when sacrificial parts of the mechanical seal are wearing at an acceptable rate. The gland is not sacrificial. If you have chosen a corrosion resistant material there is no reason for this part to be considered sacrificial. Nothing is supposed to be rubbing against this part so there is nothing to wear out. The dynamic O-ring is not sacrificial This elastomer should have been selected for chemical compatibility with the product you are sealing and any cleaners or solvents that might be flushed through the lines.
All elastomers have a high and low temperature limit.
This O-ring should have been selected to operate well within that range. The static O-ring is not sacrificial. Same rules as the dynamic O-ring, but not as critical. A small amount of swelling might not fail the seal but a great deal of swelling could break the hard face because the O-ring is mounted in the hard face inside diameter and any swelling would put this face into tensile stress where most hard materials are weaker. The stationary face holder is not sacrificial.