rub salt in someone's wounds vs twist the knife

rub salt in someone's wounds

verb
  • To make a painful situation even worse (even with the best of intentions). 

twist the knife

verb
  • To deliberately do or say something to worsen a difficult situation or increase a person's distress, irritation, or anger. 

How often have the words rub salt in someone's wounds and twist the knife occurred in a corpus of books? (source: Google Ngram Viewer )