grind down vs walk all over

grind down

verb
  • To weaken someone's morale over a long period. 

  • To make something hard smaller and smoother by gradually rubbing off tiny bits, to wear down. 

walk all over

verb
  • To dominate a person or a group; to have a person take a submissive or inferior role. 

  • To easily beat a competitor in a contest; to win without much effort. 

  • Used other than figuratively or idiomatically: see walk, all, over. 

How often have the words grind down and walk all over occurred in a corpus of books? (source: Google Ngram Viewer )