You can obtain the Current Project Resource Rates by the following code in Visual Basic for Applications:

Public Sub UpdateCostRates()
   Dim ProjectName As Project
   Set ProjectName = ActiveProject
   Dim N As Assignment
   Dim Names As String
   For Each T In ProjectName.Tasks
      For Each I In T.Resources
         For Each P In I.Assignments
            Set N = P
         Next P
         For Each PR In I.CostRateTables(N.CostRateTable + 1).PayRates
            Names = Names & T.Name & " - " & I.Name & " - " &
               I.CostRateTables & (N.CostRateTable + 1).Name
               & " - " & PR.StandardRate & " - " &
               PR.EffectiveDate & vbCrLf
         Next PR
      Next I
   Next T
   MsgBox Names
End Sub