[{"_id":"5485asasansja","users":["xyz@xyz.com","abc@abc.com"],"remote":{"bytes":123,"source":"some source"}},{"_id":"5885asaskaia","users":["pqr@xyz.com","abc@abc.com"],"remote":{"bytes":345,"source":"another source"}}]

db.collection.aggregate([{$unwind:"$users"},{"$group":{"_id":null,"data":{"$push":{"k":"$users","v":"$remote"}}}},{"$replaceRoot":{"newRoot":{"$arrayToObject":"$data"}}}])