Difference between index, refresh and flush time

I have 4 nodes + master, indexing time per each is ~0.5ms. It means that index velocity is 10k docs/s. (2k/s for each node). The problem is that my script, which sends data to elastic works much longer. Refresh and flush time vary between 15-20ms. Am i right, that all refresh, flush and index time summed up are time of whole operation of sending and getting response from elastic? When I set refreshing ElasticHQ for 1s I can say that docs count is increasing something like 100docs/s. Well?