As water is a conductor of electricity, when a phone gets wet you should turn off the phone immediately and then remove the battery as soon as you can, (or even just remove the battery if you can, it is quicker). This is to prevent more damage to the components caused by errant circuit paths being created by the water. As there is always power connected to the phone, due to the presence of water there is the possibility of components being exposed to voltages or currents that they were not designed to cope with, (even if the phone is turned off- the power switch does not isolate the battery from the phone). There is also the corrosive electrolysis effect between the elements that are found in water, (whether they are added deliberately or not, think chlorine, fluoride, natural minerals etc) and the metals contained in a phone which occurs and is aided by the supply of electricity.
Once the battery has been removed, then the phone can be disassembled, so that all the parts can be very carefully and gently cleaned with Isopropyl Alcohol 90%+ and a soft brush (you do not want to brush components off the systemboard) and allowed to completely dry. The corrosion will be removed by the alcohol.
When satisfied that you have done all you can, re-assemble the phone and hopefully it just may turn on successfully. If it doesn't, then perhaps some components have been damaged and the phone would have to be taken to a reputable, professional phone repair centre where hopefully they may be able to fix it.
Rice is good to eat but does nothing to mitigate the corrosive effects of water or the damage that can be caused to components by electric currents flowing where they shouldn't because of errant circuit paths created by water.