using (FeatureClass featureClass = featureLayer.GetFeatureClass())
{
  // Insert rows using InsertCursor
  EditOperation insertCursorEditOperation = new EditOperation();
  insertCursorEditOperation.Name = "Create rows using InsertCursor";
  insertCursorEditOperation.Callback((EditOperation.IEditContext editContext) =>
  {
    using (InsertCursor insertCursor = featureClass.CreateInsertCursor())
    using (RowBuffer rowBuffer = featureClass.CreateRowBuffer())
    {
      for (int i = 0; i < countRowsToCreate; i++)
      {
        // Fill in RowBuffer using your data here

        insertCursor.Insert(rowBuffer);
      }
      
      insertCursor.Flush();
    }
  }, featureClass);
}