what causes these symptoms scoring on pistons, head? Photos attached

[waternewbie]

2003 Seadoo gtx 185 SC
Pitting and burn spots on piston and cylinder head.

What causes this?

 

[Rikky001]

Saltwater ingestion.

 

[waternewbie]

Saltwater ingestion.

Thank You ok, now I will go on and rebuild . I picked up this unit for $500 with his problem, when I tore it apart these symptoms didn't look familiar. We live in land freshwater is where we're at.

 

[Jafo30]

Looks like pinging as salt water all would look the same