[{"rates":[{"category":"Web","seniorityRates":[{"seniority":"junior","rate":100},{"seniority":"intermediate","rate":135},{"seniority":"senior","rate":165}]}]}]

db.collection.update({},{$set:{"rates.$[].seniorityRates.$[j].seniority":"debutant"}},{arrayFilters:[{"j.rate":{$lte:100}}]})